1. Field of the Invention
This invention relates to a seat sliding apparatus for vehicles, and more particularly to a seat sliding apparatus for vehicles in which a seat rail is reinforced.
2. Description of the Prior Art
A conventional seat sliding apparatus for vehicles is shown in FIG. 3, namely, an upper rail 6 and a lower rail 7 are connected to each other through a roller 8 and a steel ball 9, so that the smooth sliding can be attained between upper and lower rails 6, 7. This type of the art is disclosed in Japanese Utility Model Open Letter No. 61(1986)-138729. However, a separating load is applied on both rails 6, 7 upon using this type of the slidable seat. When the separating load is applied to the lower rail 7, a lateral wall 7a of the lower rail 7 is inwardly inclined and deformed as clearly viewed from FIG. 4. Therefore, it creates a dangerous state in which the upper rail 6 is separated from the lower rail 7. The dangerous state by the separation of the upper rail 6 from the lower rail 7 depends on a frequency of use and using manner of a seat, number of years in use, and weight of a user.